NA-ATLL and J-ATLL have differentially enriched motifs in accessible chromatin regions. (A) Motif enrichment in differentially accessible regions between NA-ATLL (n = 4) and J-ATLL (n = 4) cell lines. ETS1 motif was significantly enriched in chromatin regions that were more accessible in NA-ATLL cell lines, whereas AP1 and IRF4 motifs were enriched in chromatin regions that were more accessible in J-ATLL cell lines. (B) Comparison of overall enrichment of ETS1 and AP1 motifs (percent of total peaks containing the motif) across normal Treg cells and NA-ATLL and J-ATLL cell lines. The ETS1 motif is significantly enriched in NA-ATLL cell line peaks and the AP1 motif is significantly enriched in J-ATLL cell line peaks. (C) J-ATLL cell lines have significantly greater chromatin accessibility (FDR = 0.0013) at the BATF3 intronic region (intron 2) overlapping with a previously identified HBZ binding site.¹⁷ (D) Two intronic peaks in ETS1 (intron 6) were accessible primarily in NA-ATLL cell lines. (E) Intron 6 peak 1 has been identified as an enhancer for ETS1 and the ETS family member FLI1 through direct chromatin interaction (FANTOM5³⁹). (F) ETS1 accessible peaks identified by ATAC-seq overlap with ETS1 binding sites in Treg ETS1 ChIP-seq.